/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/*
 *  Public Key layer for writing key files and structures
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#include "tls/config.h"

#if defined(MBEDTLS_PK_WRITE_C)

#include "tls/pk.h"
#include "tls/asn1write.h"
#include "tls/oid.h"

#include <string.h>

#if defined(MBEDTLS_RSA_C)
#include "tls/rsa.h"
#endif
#if defined(MBEDTLS_ECP_C)
#include "tls/ecp.h"
#endif
#if defined(MBEDTLS_ECDSA_C)
#include "tls/ecdsa.h"
#endif
#if defined(MBEDTLS_PEM_WRITE_C)
#include "tls/pem.h"
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc    calloc
#define mbedtls_free       free
#endif

#if defined(MBEDTLS_RSA_C)
/*
 *  RSAPublicKey ::= SEQUENCE {
 *      modulus           INTEGER,  -- n
 *      publicExponent    INTEGER   -- e
 *  }
 */
static int pk_write_rsa_pubkey(unsigned char **p, unsigned char *start, mbedtls_rsa_context *rsa)
{
	int ret;
	size_t len = 0;

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(p, start, &rsa->E));
	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(p, start, &rsa->N));

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));

	return ((int)len);
}
#endif							/* MBEDTLS_RSA_C */

#if defined(MBEDTLS_ECP_C)
/*
 * EC public key is an EC point
 */
static int pk_write_ec_pubkey(unsigned char **p, unsigned char *start, mbedtls_ecp_keypair *ec)
{
	int ret;
	size_t len = 0;
	unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN];

	if ((ret = mbedtls_ecp_point_write_binary(&ec->grp, &ec->Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &len, buf, sizeof(buf))) != 0) {
		return (ret);
	}

	if (*p < start || (size_t)(*p - start) < len) {
		return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
	}

	*p -= len;
	memcpy(*p, buf, len);

	return ((int)len);
}

/*
 * ECParameters ::= CHOICE {
 *   namedCurve         OBJECT IDENTIFIER
 * }
 */
static int pk_write_ec_param(unsigned char **p, unsigned char *start, mbedtls_ecp_keypair *ec)
{
	int ret;
	size_t len = 0;
	const char *oid;
	size_t oid_len;

	if ((ret = mbedtls_oid_get_oid_by_ec_grp(ec->grp.id, &oid, &oid_len)) != 0) {
		return (ret);
	}

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len));

	return ((int)len);
}
#endif							/* MBEDTLS_ECP_C */

int mbedtls_pk_write_pubkey(unsigned char **p, unsigned char *start, const mbedtls_pk_context *key)
{
	int ret;
	size_t len = 0;

#if defined(MBEDTLS_RSA_C)
	if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
		MBEDTLS_ASN1_CHK_ADD(len, pk_write_rsa_pubkey(p, start, mbedtls_pk_rsa(*key)));
	} else
#endif
#if defined(MBEDTLS_ECP_C)
		if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
			MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_pubkey(p, start, mbedtls_pk_ec(*key)));
		} else
#endif
			return (MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE);

	return ((int)len);
}

int mbedtls_pk_write_pubkey_der(mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
	int ret;
	unsigned char *c;
	size_t len = 0, par_len = 0, oid_len;
	const char *oid;

	c = buf + size;

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_pk_write_pubkey(&c, buf, key));

	if (c - buf < 1) {
		return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
	}

	/*
	 *  SubjectPublicKeyInfo  ::=  SEQUENCE  {
	 *       algorithm            AlgorithmIdentifier,
	 *       subjectPublicKey     BIT STRING }
	 */
	*--c = 0;
	len += 1;

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING));

	if ((ret = mbedtls_oid_get_oid_by_pk_alg(mbedtls_pk_get_type(key), &oid, &oid_len)) != 0) {
		return (ret);
	}
#if defined(MBEDTLS_ECP_C)
	if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
		MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, mbedtls_pk_ec(*key)));
	}
#endif

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_algorithm_identifier(&c, buf, oid, oid_len, par_len));

	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));

	return ((int)len);
}

int mbedtls_pk_write_key_der(mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
	int ret;
	unsigned char *c = buf + size;
	size_t len = 0;

#if defined(MBEDTLS_RSA_C)
	if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
		mbedtls_rsa_context *rsa = mbedtls_pk_rsa(*key);

		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->QP));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->DQ));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->DP));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->Q));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->P));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->D));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->E));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &rsa->N));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));

		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
		MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
	} else
#endif							/* MBEDTLS_RSA_C */
#if defined(MBEDTLS_ECP_C)
		if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
			mbedtls_ecp_keypair *ec = mbedtls_pk_ec(*key);
			size_t pub_len = 0, par_len = 0;

			/*
			 * RFC 5915, or SEC1 Appendix C.4
			 *
			 * ECPrivateKey ::= SEQUENCE {
			 *      version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
			 *      privateKey     OCTET STRING,
			 *      parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
			 *      publicKey  [1] BIT STRING OPTIONAL
			 *    }
			 */

			/* publicKey */
			MBEDTLS_ASN1_CHK_ADD(pub_len, pk_write_ec_pubkey(&c, buf, ec));

			if (c - buf < 1) {
				return (MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);
			}
			*--c = 0;
			pub_len += 1;

			MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(&c, buf, pub_len));
			MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING));

			MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(&c, buf, pub_len));
			MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 1));
			len += pub_len;

			/* parameters */
			MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, ec));

			MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_len(&c, buf, par_len));
			MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0));
			len += par_len;

			/* privateKey: write as MPI then fix tag */
			MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_mpi(&c, buf, &ec->d));
			*c = MBEDTLS_ASN1_OCTET_STRING;

			/* version */
			MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 1));

			MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
			MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
		} else
#endif							/* MBEDTLS_ECP_C */
			return (MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE);

	return ((int)len);
}

#if defined(MBEDTLS_PEM_WRITE_C)

#define PEM_BEGIN_PUBLIC_KEY    "-----BEGIN PUBLIC KEY-----\n"
#define PEM_END_PUBLIC_KEY      "-----END PUBLIC KEY-----\n"

#define PEM_BEGIN_PRIVATE_KEY_RSA   "-----BEGIN RSA PRIVATE KEY-----\n"
#define PEM_END_PRIVATE_KEY_RSA     "-----END RSA PRIVATE KEY-----\n"
#define PEM_BEGIN_PRIVATE_KEY_EC    "-----BEGIN EC PRIVATE KEY-----\n"
#define PEM_END_PRIVATE_KEY_EC      "-----END EC PRIVATE KEY-----\n"

/*
 * Max sizes of key per types. Shown as tag + len (+ content).
 */

#if defined(MBEDTLS_RSA_C)
/*
 * RSA public keys:
 *  SubjectPublicKeyInfo  ::=  SEQUENCE  {          1 + 3
 *       algorithm            AlgorithmIdentifier,  1 + 1 (sequence)
 *                                                + 1 + 1 + 9 (rsa oid)
 *                                                + 1 + 1 (params null)
 *       subjectPublicKey     BIT STRING }          1 + 3 + (1 + below)
 *  RSAPublicKey ::= SEQUENCE {                     1 + 3
 *      modulus           INTEGER,  -- n            1 + 3 + MPI_MAX + 1
 *      publicExponent    INTEGER   -- e            1 + 3 + MPI_MAX + 1
 *  }
 */
#define RSA_PUB_DER_MAX_BYTES   38 + 2 * MBEDTLS_MPI_MAX_SIZE

/*
 * RSA private keys:
 *  RSAPrivateKey ::= SEQUENCE {                    1 + 3
 *      version           Version,                  1 + 1 + 1
 *      modulus           INTEGER,                  1 + 3 + MPI_MAX + 1
 *      publicExponent    INTEGER,                  1 + 3 + MPI_MAX + 1
 *      privateExponent   INTEGER,                  1 + 3 + MPI_MAX + 1
 *      prime1            INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
 *      prime2            INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
 *      exponent1         INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
 *      exponent2         INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
 *      coefficient       INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
 *      otherPrimeInfos   OtherPrimeInfos OPTIONAL  0 (not supported)
 *  }
 */
#define MPI_MAX_SIZE_2          MBEDTLS_MPI_MAX_SIZE / 2 + \
MBEDTLS_MPI_MAX_SIZE % 2
#define RSA_PRV_DER_MAX_BYTES   47 + 3 * MBEDTLS_MPI_MAX_SIZE \
+ 5 * MPI_MAX_SIZE_2

#else							/* MBEDTLS_RSA_C */

#define RSA_PUB_DER_MAX_BYTES   0
#define RSA_PRV_DER_MAX_BYTES   0

#endif							/* MBEDTLS_RSA_C */

#if defined(MBEDTLS_ECP_C)
/*
 * EC public keys:
 *  SubjectPublicKeyInfo  ::=  SEQUENCE  {      1 + 2
 *    algorithm         AlgorithmIdentifier,    1 + 1 (sequence)
 *                                            + 1 + 1 + 7 (ec oid)
 *                                            + 1 + 1 + 9 (namedCurve oid)
 *    subjectPublicKey  BIT STRING              1 + 2 + 1               [1]
 *                                            + 1 (point format)        [1]
 *                                            + 2 * ECP_MAX (coords)    [1]
 *  }
 */
#define ECP_PUB_DER_MAX_BYTES   30 + 2 * MBEDTLS_ECP_MAX_BYTES

/*
 * EC private keys:
 * ECPrivateKey ::= SEQUENCE {                  1 + 2
 *      version        INTEGER ,                1 + 1 + 1
 *      privateKey     OCTET STRING,            1 + 1 + ECP_MAX
 *      parameters [0] ECParameters OPTIONAL,   1 + 1 + (1 + 1 + 9)
 *      publicKey  [1] BIT STRING OPTIONAL      1 + 2 + [1] above
 *    }
 */
#define ECP_PRV_DER_MAX_BYTES   29 + 3 * MBEDTLS_ECP_MAX_BYTES

#else							/* MBEDTLS_ECP_C */

#define ECP_PUB_DER_MAX_BYTES   0
#define ECP_PRV_DER_MAX_BYTES   0

#endif							/* MBEDTLS_ECP_C */

#define PUB_DER_MAX_BYTES   RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \
RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES
#define PRV_DER_MAX_BYTES   RSA_PRV_DER_MAX_BYTES > ECP_PRV_DER_MAX_BYTES ? \
RSA_PRV_DER_MAX_BYTES : ECP_PRV_DER_MAX_BYTES

int mbedtls_pk_write_pubkey_pem(mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
	int ret;
	unsigned char output_buf[PUB_DER_MAX_BYTES];
	size_t olen = 0;

	if ((ret = mbedtls_pk_write_pubkey_der(key, output_buf, sizeof(output_buf))) < 0) {
		return (ret);
	}

	if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_PUBLIC_KEY, PEM_END_PUBLIC_KEY, output_buf + sizeof(output_buf) - ret, ret, buf, size, &olen)) != 0) {
		return (ret);
	}

	return (0);
}

int mbedtls_pk_write_key_pem(mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
	int ret;
	unsigned char output_buf[PRV_DER_MAX_BYTES];
	const char *begin, *end;
	size_t olen = 0;

	if ((ret = mbedtls_pk_write_key_der(key, output_buf, sizeof(output_buf))) < 0) {
		return (ret);
	}
#if defined(MBEDTLS_RSA_C)
	if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
		begin = PEM_BEGIN_PRIVATE_KEY_RSA;
		end = PEM_END_PRIVATE_KEY_RSA;
	} else
#endif
#if defined(MBEDTLS_ECP_C)
		if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
			begin = PEM_BEGIN_PRIVATE_KEY_EC;
			end = PEM_END_PRIVATE_KEY_EC;
		} else
#endif
			return (MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE);

	if ((ret = mbedtls_pem_write_buffer(begin, end, output_buf + sizeof(output_buf) - ret, ret, buf, size, &olen)) != 0) {
		return (ret);
	}

	return (0);
}
#endif							/* MBEDTLS_PEM_WRITE_C */

#endif							/* MBEDTLS_PK_WRITE_C */
